The Cipher Conundrum
by voodoogirl360
Summary: <html><head></head>Bill Cipher is a demon, and, as all demons tend to do, he gets bored. And when Bill Cipher gets bored, his prime destination is usually the unfortunate town of Gravity Falls. Things quickly get out of hand, however, when he falls in a certain stream (curse that branch) and finds himself far too...mortal for his tastes. Monsterfalls. Cover image credit goes to zilleniose..</html>
1. Chapter 1

The thing about humor that lots of people fail to understand, Bill mused as he staggered through the underbrush, is that jokes stop being funny after the first few times you tell them. Or in his case, feel them.

Pain had stopped being hilarious right around the time he got his newly-minted leg caught in a bear trap that he was still beating himself up over for having missed. The thing was _bedazzled_, for fuck's sake. He hadn't the slightest idea how to get the accursed thing _off_, either. He'd been trying not to think about it for the past 2 hours, which was easier said than done considering it made his foot explode in agony every time he tried to take a step. How these useless fleshsacks survived for more than a day apiece, he'd never know.

Really, it wasn't the pain that got to him so much as the indignity. He, Bill Cipher, the most powerful being ever to grace this miserable plane of existence, was stuck as a measly human for who knows how long, all because of that stupid branch, and that stupid law of gravity that he shouldn't even be affected by in the first place because seriously, hello, _demon_, can physics catch up with his importance already, and that stupid, _stupid_ stream. When he got his powers back, he was going to burn this entire forest to the ground.

He stopped, resting against a nearby tree trunk. There it was again. His vision had gone all fuzzy and he'd had this horrible…_dizzy_ feeling. He hoped he wasn't dying. That would be ridiculously inconvenient. He took a few deep breaths (that was another thing. Breathing was so _impractical_. He was still forced to do it to survive, unfortunately, as he found out after nearly passing out after being human for a mere 30 seconds), and forged on – only to have his legs give out from under him. He groaned. Fantastic. Of all the times for his useless meat sticks to stop functioning, it had to be now. He'd just started to hear the sounds of civilization a few minutes ago and everything. So much for his dramatic entrance. He was planning on getting free hot chocolate by disarming the locals with a good sob story, too. It'd been ages since he'd had real food.

He rolled onto his stomach with some effort, because grass smelled disgusting and hell if he was letting his last moments go down like that. It was getting hard to think, so he decided to stop doing that, except his thoughts didn't want to turn off for some reason. That was annoying. How were you supposed to focus with all this background noise in your head?

Whatever. Not like it was going to be there for much longer.

Not like _he_ was going to be there for much longer.

He heard the soft patter of footsteps. Some kind of deer, by the sound of it. He turned his head in what he was fairly sure was the direction of the sweet little woodland buddy and said drunkenly, "You know I ripped the teeth out of one of you once?" He giggled. "I put them back right after, don't worry."

"Uhhhh," the deer said.

Huh.

A talking deer was pretty new.

Before Bill had time to fully appreciate the ramifications of sentient cervids, however, the blackness that had been threatening the edges of his peripheral vision for a while now swept down upon him as if drawing the curtain on this unfortunate spectacle, and he knew no more.

The first thing Bill was acutely aware of when he awoke was that his jacket had been removed. He'd need to get that back. He liked that jacket. Maybe he could find a way to incorporate it into his regular outfit. Suits didn't really cooperate with triangular bodies, sadly. One of the benefits of being a human, he supposed. The very, very few benefits.

The second thing he was aware of very shortly after was a large, beaming grin taking up his entire field of vision.

Bill considered for a moment, before swiftly crashing his head into the offending mouth.

The grin and its owner fell back with a splash, giggling in a slightly strained manner. Bill laughed too, some good humor returning. Pain was a lot funnier when it happened to other people, he was finding.

Upon further examination of the scene, the grin was revealed to belong to a very familiar preteen, who was rubbing her teeth as she sat in what looked to be a small portable cart filled to the brim with water, smile still unfortunately in place. It didn't take keen observational skills (which Bill possessed in spades, but that's beside the point) to notice the shimmering cerise scales of her shiny new mermaid tail. He grinned. It would seem ol' Fluvius Cantatis had nabbed another victim besides himself.

"Ow," she said, still chuckling lightly. "You sure have a hard head. Though I guess I deserved that for the bear trap."

"That was yours?" He grunted in annoyance. "You're more trouble than you're worth, kid. Why did you even put them there?"

"To keep monsters away, _duhhhhhh_," she said, reaching over to boop his nose. "Where've you been?"

"Oh, lots of places," he said lightly. "_Lots _of places. I just came through here recently, actually. Think I might remember you. You were the one who gave that puppet show, weren't you? _Loved_ it."

"Yeah, you could say it went out…WITH A BANG." She made finger pistols. "BOOSH."

"Oh, definitely. It felt like such an…EXPLOSIVE FINALE." He cackled. "Especially since I got front-row seats to the whole thing." He tapped his chin. "Something's different about you, though. New haircut?"

"Oh, yeah, the tail." She waved it around, showing off her smooth tailfin. "It's pretty great, right? Maybe I can visit Mermando now!" She paused. "He's a merman. We're totally soulmates."

"Cute," Bill said distractedly, already losing interest in the conversation. "Where's that brother of yours?"

"Oh, Dipper? He went to get Grunkle Stan." She grinned. "Heheh, he was pretty worried about you, all zonked out in the woods like that." Then the grin faded as realization hit. "Hang on, how do you know I have a –"

Bill was saved from having to cover his slip-up when the door swung open, distracting the both of them (much to Bill's relief – in all honesty, he was a _horrible_ actor, mainly relying on his mind magic to fill in the gaps, which, being a human now, he had precisely none of), as a small deertaur entered the room, hurriedly pulling on the stony gray hand of a gargoyle, of all things. Bill had to stifle a snort. Trust Fluvius to get it right on the money. That old coot certainly had protective instinct to spare.

"All right, all right, I'm coming, kid," Stanford grumbled, snatching his hand away from the other's, causing him to stumble on his still-unsteady hooves, briefly scrabbling for purchase on the wooden floor. "I'm made of stone, I don't move like I used to."

"But what if he's really hurt? He had his leg caught in a bear trap and I'm pretty sure he was delirious!" Haha, oh, kid. He's _always_ delirious. Stanford was having none of it, though, waving aside the kid's worries with a dismissive hand.

"Ah, come on, this stuff always looks worse than it is. I'm sure he's –" Stanford stopped abruptly as he caught sight of Bill, who was just realizing that, as a lanky, sandy-haired male wearing a very distinctively-patterned suit complete with little black bow tie and eye patch, he was perhaps not as well-disguised as he would like. He had a horrible feeling that Stanford was realizing that too.

Stupid, _stupid_ stream.

Play it cool, Bill. He waved languidly. "Fine? Just dandy! I'm so touched you care." He fluttered his eyelashes. "You're Grunkle Stan, I'm assuming?" He smiled, wide and toothy. "Nice kids you got here." His grin widened as the old man's face went literally ashen. Good to see he still had his touch, even as a human.

"Yeah. Yeah, I do." He stepped forward. "Go get some bandages for our, uh…guest, kids. I'm gonna have a little chat with him." Eagerly, the kids obeyed, Pine Tree carting his sister off to who knows where. She waved brightly at him as they left, the door closing shut behind them with an awful sort of finality. Slowly, Stan turned to Bill. His voice was deadly calm, though the tenseness of his wings gave away his inner fear and anxiety.

"I'm going to give you," he said softly, stepping towards the newly-mortal demon, "one chance to explain what the hell you're doing here, Bill."

Bill chuckled. "That's a stony disposition you've got there, Stanford. I'm not up to anything, I promise. Just passing by, that's all." He drew his face into an exaggerated pout (the human body was _wonderful_ at expressions). "Can't I drop by and visit my favorite saps?"

"Not if it means endangering those two," he growled. "I made a promise to their parents. I'm not gonna let you harm a single hair on their heads."

"Hoo hoo. Spicy." He booped the angry gargoyle on the nose. "Always so protective of your kin." He grinned, a malicious glint entering his eyes. "Too bad you can't always save them in time, hm?"

With a roar that carried the force of an avalanche, Stanford lunged forward, knocking the wind out of Bill as he pinned him to the wall. Bill gasped, scrabbling uselessly at where his throat was being held uncomfortably tight by the gargoyle's iron grip.

"Don't you DARE bring him into this," he snarled. "You know I did everything I could have done."

"Sure – _gak_ – sure didn't seem that way to me," he wheezed, chuckling breathily even as his face turned an odd shade of blue. "It's been thirty years, old man, and you're still guilty about it. Maybe – _hahh _– maybe that's because deep down you realize that it was all –" Stanford growled warningly, but Bill continued, smirking.

"Your – "

"DON'T SAY IT!"

"_Fault,_" Bill whispered, leaning in and spitting the word in his face with the last of his air. Stanford screamed in a blind rage, and flung Bill away, slamming him into the opposite wall.

There was a sickening crack, and Bill screamed, high-pitched and pain-filled, slumping to the ground and cradling his arm, which hung at an unnerving angle. The sound seemed to snap Stanford out of his fury, and he turned, eyes widening as he took in the sight. He stepped forwards cautiously, looking at the demon with something almost akin to concern.

Bill didn't notice, or particularly care.

He was in pain. A lot of pain. He'd experienced pain before, naturally (a highly enjoyable romp with a certain meddling 12-year-old's body came to mind), but that, he realized, had been nothing compared to this. His arm was burning, searing with a fire that, for once, he could not control, and the sensation was unnerving, to say the least. He found himself, for the first time in a very, very, _very_ long while, wishing he could simply cease to exist, or at the very least find something, anything, to make the fire stop.

Pain, he decided, was not hilarious.

Pain was not hilarious at _all_.

He felt a pair of heavyset arms pick him up and carry him to his original resting place, and he couldn't help but wince every time his arm was jostled. Gently, Stanford set him down, and looked awkwardly at the battered figure before him. Bill refused to meet his eyes.

"…You're hurt," he said finally. "I don't think I've ever seen you get hurt before. Heck, I didn't think it was _possible_."

"Shut up," Bill muttered bitterly, still nursing his arm.

"Did…did something happen –"

"_No_," Bill interrupted, tone just a tad harder than he'd intended it to be. He flinched, and it did not go unnoticed, as Stanford's eyes widened, a theory already forming.

"It was the river, wasn't it?" he said with a touch of wonder. "The, the Fluvuvie-something?"

"Fluvius Cantatis, and _yes_," Bill spat. "Yes, are you happy now, YES. Feast your eyes! The great and powerful Bill Cipher reduced to one of you fleshbags." He grimaced. "I don't know how the hell you stand it." He gestured to his arm. "What…" He glared at the broken limb as if it had committed a personal offense against him. "What is this? What did you do to me?"

Stanford blinked. "What? Oh. Oh, uh, it's. It's probably a broken arm."

"How do you fix it?"

The gargoyle couldn't help but chuckle. "Time, and keeping it real still."

"You're serious?" Bill looked at him incredulously as he nodded, grinning. "That's so _slow_."

"One of the perks of bein' a gargoyle. Got crazy healing powers." He cackled. "Ahh, man, this is rich! The only human in a town fulla monsters!"

"When I get my powers back, I am going to kill you all," Bill said, voice dripping with venom. Stanford simply patted him on the back, still chuckling good-naturedly.

"I can't take ya seriously when you're like this. You're like one of those yappy little dogs!"

Bill scowled. "I am a being of _phenomenal cosmic power_, you daft fool, and I will _not be spoken to like that_."

"Not right now ya aren't," he teased, poking the former demon in the side. Bill growled, swatting his hand away.

"_Stanford Pines I swear I will wreak vengeance on you and your entire family –" _

His vow was abruptly interrupted as the Wonder Twins barged in, Shooting Star managing to balance a box of bandages on her head as her twin frantically pulled the cart to a halt.

"Guess who got _bandagesssssss~!" _she sang out, then paused, looking at the scene before them. Both parties were significantly more disheveled than they had been when the pair had left, with the dapper gentleman clutching his arm and caught in the middle of yelling angrily at their great-uncle with an expression that was highly reminiscent of an angered kitten.

She raised an eyebrow. "Grunkle Staaaaaaan," she began accusingly.

Stan hurriedly cleared his throat. "Kids!" he said hurriedly. "This is Will, uh…Will Nemo! He's gonna be staying with us for a while until his arm and leg heal."

"Arm? But I thought his leg was the only thing that got hurt," Dipper said confusedly.

"His arm's broken too. Freak accident. Don't ask me to explain, I can't explain." He took on a decidedly shifty look. "Explain what? I don't know what you're talking about!"

"You're kind of terrible at this, aren't you, Stanford," Bill said flatly from behind the nervous gargoyle. He stood in one fluid motion, wincing slightly as he put weight on his injured foot but recovering nicely. He stepped forward, elegantly reaching out his good hand to the pair.

Mabel took the hand eagerly. "I'm Mabel! Mabel Pines. This is my brother Dipper."

"Hey," Dipper said, waving slightly.

Bill shook it firmly, feeling as if he was getting back on familiar ground at last. If there was one thing he was good at, it was shaking hands.

Oh yes, he was _very_ good at shaking hands.

"Your grunkle already introduced me, but I'll do it again," he said smoothly. "Will Nemo, traveling magician." His grin would have put the Cheshire Cat to shame. "I can't _wait_ to get to know you better."

This, he thought to himself as he allowed Mabel to sternly order him back to his seat so he could be bandaged, watching Stanford warily eyeing him from the corner, now _this_?

_This_ was truly hilarious.


	2. Chapter 2

It was official, Dipper thought as he watched the newcomer struggle to shelve some product Grunkle Stan had tasked him with restocking and glare daggers at his tourniquet-clad arm for the fifth time that hour.

William Nemo the Third, Esquire (as he had briefly demanded the twins call him before exasperatedly calling off an excited Mabel who repeated it 20 consecutive times in an increasingly outrageous British accent) was hiding something.

The deertaur absentmindedly scratched the soft velvet of one of his long ears as he gazed down at the increasingly full pages of the small evidence journal he'd been keeping over the past few days, documenting Will's odd behaviours and quirks.

And hoooo boy, did he ever have a lot of them.

For one thing, his clothes. They were immaculate, which by itself could just have been taken as a sign of caring about his appearance, except he always wore the same suit. The exact same suit. Every day. Dipper had yet to see him take it off, and, in fact, one night when he'd been curious he peeked inside the makeshift bedroom they'd hurriedly set up for him and witnessed the bizarre spectacle of Will lying ramrod-straight on his bed, covers untouched, his suit still very much in place complete with his small black eyepatch resting comfortably over his right eye as always, and apparently deeply asleep

Then, of course, there was the complete lack of surprise at the various…changes the members of the household had undergone. He'd laughed uproariously at Soos' booming voice and warped appearance and proceeded to rearrange his limbs into a truly Lovecraftian configuration, much to the handyman's delight (and the general public's utter terror), had spent hours up on the roof with Grunkle Stan the other night talking about…something, and, worst of all, had _helped Wendy in the shop yesterday for like, two hours._ _Straight_. This was clearly an act of psychological warfare.

Finally, though, and perhaps strangest of all…

Will knew things.

Things he shouldn't have possibly been able to know, given his status as complete and utter stranger. He knew about Dipper's birthmark, teasing him casually about it one afternoon while he was sweeping the floor (Grunkle Stan insisted on keeping the Shack clean despite the flow of customers being depressingly low as the town's supernatural population grew). He knew about Gideon, claiming to have 'tangoed with that lovesick midget one too many times for his taste'.

Plus there was the matter of his knowing the name of the enchanted stream that had started all this insanity, despite never reading or even touching the journal and claiming never to have gone near the place.

There was no doubt about it. _Something_ was going on with Will.

He just wished he knew _what_.

Closing his evidence journal with a frustrated snap, Dipper ventured out into the gift shop as nonchalantly as possible. Will turned, abandoning his shelving efforts for the moment, his ever-present catlike grin affixed firmly in place upon his face.

"Glad you finally decided to come out," he said casually, setting the offending box on the nearby counter. "I could use your help."

Dipper started, an embarrassed blush rising. "Y-you knew?" Will cackled in amusement.

"Deer feet aren't exactly subtle, kid." He gestured to the box. "But they do mean you'll make an excellent ladder."

"…Ladder?" Dipper tilted his head in equal parts confusion and trepidation.

"Sure!" He stabbed his finger to the wall. "Prop your forehooves up there."

Dipper complied, albeit warily, and soon found himself in a very awkward position. Grabbing the shelf for extra balance, he turned his head in Will's general direction. "OK, forehooves propped," he called, slightly aggravated. "What do I do now?"

"Hold still," the answer came a moment later from right behind him, and before he could do anything, his rear legs threatened to buckle under a new, unexpected weight. Bill laughed giddily, teetering unsteadily as he clambered up the deertaur's back, box in hand.

"Are you INSANE?" Dipper yelped as Will's heel dug into his back.

"You should already know the answer to _that_ question, Pine Tree!" he called down, still cackling madly. With a triumphant cry, the box was placed, and he raised his one good hand in an exultant gesture of victory.

This, of course, meant he had nothing to keep him upright on Dipper's back.

The impromptu tower swayed and fell, the two of them toppling into a messy heap. Will giggled breathily.

"Let's do that again!"

"No," Dipper said flatly, shoving the teen off of him with a grunt and rising to his feet. Ugh, he was going to have foot-shaped bruises all _over_ his back, he just knew it.

"Ahh, you're no fun, kid." He grinned. "Besides, I might need you again!"

"What, as your personal stepping stool?"

"Sure!" He picked himself up, adjusting his tourniquet and wincing slightly as he did so. "We could even strike a deal! You help me out in the shop, and in return I'll help you look for that cure you're so eager to find." He extended a hand with a flourish. "Whaddaya say, kid?"

Dipper paused, considering. On the one hand, he _did_ need all the help he could get researching a cure for the water's enchantment; there wasn't anything in the book on a possible cure, and the author's writings on the stream stopped abruptly halfway through the entry.

On the other hand, though…

He looked at the hand, and at its owner's expectant grin, and felt a chill run up his spine. There was something about this, something he couldn't quite put his finger on, that felt familiar. Familiar, and very troubling.

Something told him that Will Nemo could not be trusted.

Slowly, he shook his head. "I'll pass," he said, keeping his voice casual. Will pouted.

"Aw. We woulda made a great team, you and I!" He shrugged. "Well, if you ever change your mind, I'll be here for you." He leaned in, waggling his eyebrows. "Ready to make a _deeeeeeal_!" With that he turned back to his shelving, laughing at some joke that only he knew the punchline to.

Dipper stood there for a moment longer, then walked away, mind whirring with thought. He'd heard that somewhere, he _knew_ he had. It was right on the tip of his tongue, if he could only just –

His eyes widened as he thought back to something Will had said just moments prior.

"_You should already know the answer to _that_ question, Pine Tree!"_

_Pine Tree._

Only one person had ever called him that.

Or one demon, rather.

The notebook dropped from his trembling hands as he turned, slowly, to look at the man in the gift shop, cheerfully humming some unknown tune to himself as he struggled to lift a heavy package with only one arm.

The knowledge. The eye patch. Now that he thought about it, his laugh was exactly as he remembered it too, high-pitched and nasal, making you feel as if you'd lost a game you didn't know you were playing.

He knew what William Nemo the Third, Esquire was hiding.

Slowly, then gaining speed, Dipper took off out the front door towards the lake, where he knew Mabel would be at this time of day.

And inside the gift shop, Bill watched him go, grinning.

_Finally_.


	3. Chapter 3

Being a mermaid was _the best_.

Mabel propelled herself swiftly through the cool lake water, whooping as she breached the surface and came back down again with a truly immense splash. She was pretty sure that was her highest leap yet! Maybe she could finally get up the waterfall now. That would be _awesome_.

Of course, what would be the absolute most awesome would be seeing Mermando. She knew that was probably impossible, though. He had his family, and she had hers. Still, it would have been nice to swim with him for _realsies_.

Her fantasies were interrupted by a faint call from the water's surface. She perked her ears, listening intently. Was it just her imagination?

No, there it went again. She swam up and popped her head out of the water, looking around for the source of the voice. Then she saw a small deer-shaped figure waving its arms and yelling at her from on the dock. She rolled her eyes. Of course it was Dipper. She dived under once again, coming up right at the edge of the dock to spare her brother's voice.

"Heya, bro-bro," she said cheerfully. "What's shakin'?"

Right away she could tell something had gotten him worked up. His eyes were wide, and darted around every few seconds, as though expecting someone to jump him at any moment. She was also getting pretty good at reading his deer-y ears (hehe, rhymes), and right now they were perked up as high as they could go.

That usually meant trouble.

He gave a shaky breath. "OK, Mabel, you have to listen to me. You know the new guy? Will?"

"You meeeean…" She put on an imperious air, miming a monocle for good measure. "William Nemo the Third, Esquire?"

He rolled his eyes. "Yeah. That guy." He leaned in, looking around furtively. "I…I think he might be Bill."

Her jaw dropped. "No _way_."

He nodded seriously. "Way. I don't know why he's here, or what he's up to, but it can't be good."

"No kidding." She frowned, concerned. "So what're we gonna do about him?"

"Uhh." He paused, sheepish. "I…hadn't really thought that far. Maybe corner him and force him to reveal his identity?"

"Sounds like a plan to me!" She grinned wildly, then gasped. "You realize what this means, right?"

Dipper's brow furrowed, confused. "What do you –" His face fell, and he said, with an edge of dull horror, "It came, didn't it."

"It came."

Dipper sighed with an air of impending doom. "I'm going to regret letting you get that thing, I can feel it."

"Never," she said playfully, sticking her tongue out. "Now come on, Dipping Sauce! We've got a _demon_ to catch!"

* * *

><p>One of the downsides to being a deertaur, Dipper was quickly finding, was the skittishness.<p>

His ears flicked around, listening tensely for every sound as he stood still as a stone, outside the door to Will's room, a feat that was becoming more and more difficult to do every second as his nerves ramped up.

Where _was_ he? A quick check had confirmed he'd finished his shelving duties, but was frustratingly absent from everywhere else in the Shack he'd looked as well. Had he gone outside? He did seem to take great relish in lying up on the roof (probably enjoying the sensation of getting sunburned, Dipper thought, shuddering at the demon's odd, nigh-masochistic streak). If he was, that didn't bode well for Dipper's plan. Deer feet were not the best at climbing rooftops, especially with the level of experience he had with them.

Or maybe, he thought nervously…

Maybe he was watching Dipper right now. Watching, and waiting for the perfect time to attack.

"Don't turn around, don't turn around, don't turn around," Dipper began softly chanting to himself, voice and legs quivering with ill-disguised terror. Every instinct was telling him to run, to get out of there as quickly as humanly (deertaur-ly?) possible, but he had to stay strong, he had to stay there. Mabel was right around the corner, he reminded himself. Everything would be fine, everything would be fine, everything would be –

"Boo," a familiar voice said softly right in his ear.

Dipper bolted before he even thought about what he was doing, making a noise more akin to a faun than a human and crashing into the opposite wall, legs still making ineffective running motions for a few seconds. Groaning, he turned to see Will, who was clutching his sides as if he thought they would burst, convulsing with paroxysms of laughter.

Wiping a tear from his eye, he straightened, the cackling fit passing. "Ahh, that was _priceless_. You're so easy to get a rise out of it almost takes the fun out of it, kid." He grinned. "Almost. So whatcha need?"

Dipper started, quickly righting himself. "A-ah! Right!" He took a deep breath, positioning himself squarely in the middle of the small, closed-off hallway, and yelled at the top of his lungs, "MABEL, _NOW!_"

"Kay!" a faint voice called back.

Then there was silence.

The two stared at one another, Will with a slightly bemused expression, Dipper struggling to maintain his confident stance even as the silence dragged on.

Will glanced around. "So is something supposed to happen, or…?"

Then the rumbling began.

Will turned with surprise, looking for the source – and his jaw dropped.

Rolling down the hall towards him, crushing stray pieces of furniture as it went, was a massive, fuschia-tinged hamster ball, and swimming forwards with all her might, looking like the happiest mermaid in the world, was Mabel. She waved, then began rolling the ball with her hands, its speed picking up to a worrying rate.

"The jig is up, Will, or should I say, _Bill?_" Dipper yelled over the din. "Get out of that body, or you'll get to experience a whole new kind of pain – getting crushed by a human-sized hamster ball!"

"Rock ON!" Mabel said fiercely, pumping her fist.

For a long moment, Bill did not respond.

Then a chuckle escaped his lips.

Then a giggle.

Then, much to the confusion (and mild terror) of the twins, Bill began to laugh, long and loud. He walked over to the ball, placing a hand on its rolling surface and stopping it easily, much to Mabel's consternation, and turned to Dipper, who took an unconscious step back, ears flattening in fear.

"B+, kid, B+! You almost got it!" He clapped good-naturedly, then bowed. "Thought you'd never catch my hints. You have _no_ idea how boring it was to play 'William Nemo' all day." His face snapped into a frown so quickly it was slightly unnerving. "But you didn't quite figure it out all the way, did you, Pine Tree?"

"Wh-what are you planning?" Dipper stammered. The demon gasped in mock surprise.

"Me? I'm not planning anything! I just want to help you find that cure." He crossed his heart. "Demon's honor. Not that I have any," he continued, chuckling, "but you get the idea."

"Yeah, like I'm gonna believe that. The last time you offered to help me, you took my body and tried to destroy the journal!"

"Oh, pshhhh," he said, waving his hand dismissively. "Water under the bridge. Besides, you think I'm offering to help you out of the goodness of my heart? I like you, kid, but I don't like you _that_ much." He leaned against the wall nonchalantly. "No, I have my own reasons for wanting to rid this town of the Fluvius Flu. Reasons you," he jabbed his thumb at Mabel, who had long since lost interest and was now making ridiculous faces by pressing her nose and mouth against the plastic of her ball, "and your idiot sister don't need to know _anything_ about. Capiche?"

Dipper crossed his arms. "And how am I supposed to trust you?"

"Trust's such an overrated thing, Pine Tree! We'll be partners of necessity. You leave well enough alone, and I'll get you and your precious town back to normal." He extended a hand that was curiously devoid of the customary blue fire. "Do we have a deal?"

Dipper didn't even have to hesitate. "No," he said flatly, turning and beginning to walk down the hallway. "C'mon, Mabel, let's go."

"Hey, wait!" Bill said indignantly, but Dipper didn't turn around. He'd made a seemingly innocent deal with the demon once and reaped the consequences; he wasn't about to do it again.

Then he stopped in his tracks as Bill spoke one last time, in a small, defeated tone.

"Please."

He turned, slowly. "What did you say?"

Bill refused to make eye contact. "You heard me the first time, kid. I'm not saying it again."

Dipper's head tilted. "Are…you feeling okay?" he said, inwardly boggling at the fact that he was actually feeling _concern_ for the demon who had nearly ruined his life not once, but twice.

"I'm fine," he shot back, a little too quickly. "You know what, forget it. I'm Bill Cipher, I can solve this on my own." He turned, hands in his pockets, expression unreadable. "Hope you like staying a deer forever."

He stalked off down the hall past Dipper, his movements quick and jerky, bumping into the deertaur as he passed. Dipper watched him go silently, unsure of what to say or think.

With a sound like two massive millstones grinding together, Mabel rolled up behind him.

"What was THAT about?" she said, tracing a question mark with water on the wall of her hamster ball.

"I..." Dipper paused. "I don't know."

* * *

><p>Five hours.<p>

That was how long Bill had been gone.

Five whole hours with no sign of the energetic demon.

Dipper hadn't been counting, of course. He just happened to notice that when he glanced at the clock for the 7th time that minute.

Because if he was worried for that backstabbing, conniving…

Desperate, desperate enough to beg Dipper to let him help, to say _please_…

That backstabbing, conniving, _very good at lying he wasn't worried_ monster, then there was something very wrong with him.

Absentmindedly, he noticed that he had chewed his pencil in half. He groaned and tossed it into an ever-growing pile of pencil nubs, pulling another out of the jar Stan had quietly and thoughtfully placed next to him after seeing the look of intense worry and confusion on his face.

He had been trying without success to figure out what Bill could be planning this time based on his earlier comments and reactions, and had so far been coming up with nothing but dead ends, much to his frustration.

Well, that wasn't entirely true, he supposed. There was one viable conclusion he'd come up with. One conclusion that, no matter how hard he tried to come up with alternatives, he always seemed to end up coming back to.

Bill Cipher genuinely wanted nothing more than to help him discover a cure for the 'Fluvius Flu', as he called it.

This was obviously impossible. He was a demon. Helpfulness was anathema to his very nature! For him to just offer to help Dipper on the conundrum that had been keeping him up at night for two weeks straight was too good to be true. There had to be some kind of catch.

And yet…

Dipper glanced at the clock again. 7:30. It was getting worryingly dark outside, and Bill still wasn't back yet.

Abruptly, he rose to his hooves, walking briskly towards the door and flinging it open.

Bill stood, frozen, in the doorway. Dipper hadn't seen him like this, well, ever. His hair, already wild to begin with, was swept this way and that, some draped over his right eye, which was missing its eye patch. His ever-immaculate suit had finally been sullied, the bright golden yellow mixed with browns and, alarmingly, some red as well.

The two stared at each other for a long, drawn-out second.

Eventually, Dipper looked away, clearing his throat and awkwardly hemming and hawing for a minute before speaking.

"Your, uh, your suit's dirty."

Bill looked down as if he was only just now noticing, gazing at it with disinterest. He made a small noise of assent, before looking back at Dipper, who fidgeted nervously under his gaze. Before he could stop himself, he thrust a hand out. Bill blinked, somewhat taken aback.

"I'm taking your deal," Dipper explained quickly. "You help me with the cure, and I don't ask why."

Bill looked at him like he'd grown a second head, but slowly raised his own hand, clasping the boy's and shaking. He chuckled lightly.

"You're insane, kid," he said with an almost affectionate air. "I like that." He cracked his knuckles. "So where do we start?"

Dipper pulled out the journal, golden hand shining brightly on the front cover. "Right here."

Bill grinned. "Perfect."

_Absolutely perfect._


	4. Chapter 4

_Thunk._

The pencil embedded itself in the rough wood of the ceiling alongside its brothers, quivering slightly with the remainder of its momentum. Bill smiled contentedly. A perfect triangle. Except… He tilted his head, considering, then grabbed another handful of pencils from the jar that sat nearby, tossing them up with pinpoint accuracy, adding a little…_personality_ to his artwork.

_Much_ better.

Next to him, Dipper grunted in annoyance. "Great," he said flatly. "That's the last pencil. Grunkle Stan is going to flip when he finds out we need another pack. _Again_."

"Stanford can go chew on his tail," Bill said, tilting his head from where it rested on the deertaur's flank to look at his erstwhile research buddy. "This," he said, gesturing grandly at his pencil portrait, which bore a strong resemblance to his natural form, "is a far better purpose for these than plain old writing."

"Mm." Dipper rolled his eyes, not looking away from the battered journal he was studying with fierce intensity. "You can explain it to him, then."

Bill cackled. "Only too happy to, kid. Nothing better than seeing that old coot get all riled up."

"What is it with you and him, anyways? You keep talking about how the two of you go way back."

"Oh, you have no idea, Pine Tree," the former demon said, chuckling to himself. Funny that Pine Tree would be the one to ask about his relationship with Stanford, considering his personality. He felt like it was 30 years ago all over again practically every other sentence with this kid. He knew Stanford saw it too. The pain in his expression when Pine Tree wasn't looking was _delicious_.

"And from _that_ cryptic response, I'm going to assume you're not going to tell me anything," he said, sighing defeatedly.

Bill grinned, bopping the kid in the back of the head. "You're learning," he sang. Then he rolled to face Dipper, grinning slyly. "You know, this would go a lot faster if we _both_ were allowed to look at the journal," he said casually, inspecting his fingernails with an air of utmost nonchalance. His response, as was expected, was a light whack on the head with the empty pencil jar.

"Not a chance, Bill," Dipper deadpanned. "Besides, I just found a lead anyways."

Bill sat up instantly, looking over the kid's shoulder with interest. "Where? What is it?"

"Well, it's not much," Dipper began hesitantly, "but…" He showed Bill a picture of what looked to be a large, dilapidated mansion. "According to the journal, there's an old mansion nearby that used to be the home of a collector of magical artifacts. There might be something that breaks curses there."

Bill shrugged, and sat up. "It's better than sitting around ticking you off all afternoon." He bowed deeply. "Lead the way, deer boy."

"Can't you teleport us there or something? I'm still not exactly the best at walking with these." He raised a foreleg for emphasis, only to quickly set it back down, flailing his arms to regain balance.

"Well, you've got to practice some time, right?" He chuckled, then stared at him, expression hard. "Now stop asking questions and start _walking, _kid." He stalked out the door, leaving Dipper to wonder what he'd said to set the demon off, before hurrying to follow him, journal in hand.

* * *

><p>There were no two ways about it; the house was, in a word, terrifying.<p>

Worn iron gates creaked slowly open as if welcoming them to the dismal mansion that stood before them which itself looked like something out of a Tim Burton film, all tall spires swaying in the wind and angular architecture that looked almost non-Euclidean in shape. Dipper trembled just looking at it, the atmosphere plucking at his nerves like the thin piano wire they were.

"I've got a _good feeling_ about this place," Bill said loudly beside him, all smiles. "Seems nice and homey, wouldn't you say, Pine Tree?"

"Y-yeah." Dipper gulped. "Homey."

He took a single, trembling step forward, then another, then another, forcing himself to keep moving through sheer willpower and determination. Bill followed, lightly humming as he skipped alongside the deertaur as if to flaunt his ease of mobility.

"It's pretty pathetic how hard of a time you're having adjusting to those new legs, Pine Tree!" he said cheerily as the two arrived at the front door, a massive wooden construction that loomed imposingly over even the lanky form of Bill. "It only took me about 30 seconds to get comfortable in yours, after all."

"That's because," Dipper grunted as he attempted to push it open, "_you_ didn't have to deal with two extra ones."

"How hard can it be?" He grinned. "Maybe you'll have to let me try them out sometime. Prove me wrong."

"Would you just help me get this door open?"

Bill pouted, walking over and throwing his weight into the door. "You're no fun when you're pissy, kid. Lighten up! If your theory's right, we're about to get rid of those pesky legs once and for –"

The sentence was never finished, as the door chose that moment to give way, sending the two of them toppling forwards. Groaning, Dipper pulled himself back into an upright position – and stared, openmouthed.

The front hallway alone was suffused in a soft glow emanating from the dozens of artifacts of all shapes and sizes lying sedately on walls and display cases, not to mention the numerous halls and doorways branching off and likely lined with treasures of their own. Dipper slowly walked over to the nearest case, which held a small, ornate brooch marked with a small placard crammed with neat, minuscule paragraphs of information.

"Narcissus Cameo – very dangerous," he read aloud. "Wearer is gripped with uncontrollable sense of vanity; do not let them see a mirror." He laughed incredulously. "This place is perfect!"

"I'll say," Bill drawled behind him, shortly followed by the sound of breaking glass. He strolled over to the deertaur, twirling a simple black cane. "I've been looking for one of these for weeks!" He stroked his chin thoughtfully. "Now if only there was a top hat around…"

Dipper rolled his eyes, moving to the next case. "Fan out and look for anything that might break curses, and _don't steal anything else_. Who knows what that cane does?"

"Who _cares_ what the cane does?" Bill said somewhat petulantly, but began examining the cases nonetheless. Despite the brief annoyance, Dipper's mood had taken a definite turn for the better. With the sheer amount of artifacts in this mansion, there was bound to be something to help solve their problem!

For the first time in a while, there was finally some hope.

* * *

><p>There was no hope, Dipper reflected glumly as he walked, accompanied by the clanking and clattering of the numerous artifacts clutched by, predictably, Bill, who occasionally piped up with a jovial description of one's effects ('and <em>this<em> one, believe it or not, causes all your food to become animate and beg you not to eat it! Hilarious, right?'). They'd searched nearly all the rooms in the old mansion, and quickly found that, while the previous owner had been fascinated by malicious enchantments, had not put much stock in their opposite number. Dipper sourly hoped the old coot had been taken out by one of his own artifacts.

His slump was broken abruptly by a long, drawn-out scream, causing him to yelp in kind and turn quickly, legs stumbling over one another and bringing him into an involuntary sitting position.

"Whoops!" said Bill, leaning down to pick up a small jewelry box that appeared to be the source of the unholy shriek. "Dropped my Wailing Box. You know how it is." He snapped it shut, the scream mercifully ceasing.

Only to be replaced by a low, rumbling growl far off in the distance.

Dipper glanced at Bill, who shrugged. "Wasn't me."

"Then who…" Dipper peered nervously down the hallway behind him, as the growl steadily increased in volume. "Or _what_ is making that?"

He blinked, rubbing his eyes. He could have sworn he saw a flash of movement in the dark hallway. Some kind of…blue glow? No, not a glow, he realized, blood freezing in his veins. Eyes. Two of them, staring back at him, solid blue and predatory.

For a long moment, there was nothing, the two of them locked in a stare-off that seemed to stretch on into eternity.

Then, with a roar, the beast charged.

Dipper sprang into action, pushing Bill towards the nearest door as best he could, the demon yelping in protest, artifacts spilling from his laden arms. He yanked it open and dashed through the open doorway, slamming it shut just before the beast reached them.

There was a pause. Dipper took a shaky breath, hardly daring to believe it had been that easy to throw the beast off their trail.

Then the wooden portal shook, cracking slightly as the beast slammed into it with all its weight. Then again, and again. It was clear what the beast was trying to do, and somehow, Dipper suspected that the old door would not hold for long.

"Pine Tree!" Bill yelled from the center of the room, drawing his attention. "You're gonna want to see this!"

The demon stood in the middle of a very familiar pattern burned into the varnished wood of the floor. Dipper's eyes widened.

"The monster outside – it's a gargoyle!" He began pacing. "I-I've seen this before. We need to make it bleed somehow, and lure it into the circle. That's the only way to break the spell!"

"That's all well and good, but I doubt either of us is going to scratch a gargoyle's hide!" Bill shouted over the rhythmic slamming and splintering of wood.

"Agh, I know! I'm trying to think…" He began rapidly flipping through the journal, muttering to himself as he searched for something, anything that would provide an escape.

"Well, think _fas_ –" Bill stopped short as, with a final, defeated groan, the door was slammed off its hinges, the furious gargoyle framed in the doorway, eyes glowing with the sky blue of mind magic. Dipper froze, the proverbial deer in the headlights. Distantly, he could hear Bill yelling something in the background, but everything seemed very far away all of a sudden.

As it roared in his face and leapt, claws singing down with lethal force, Dipper felt a pang of sadness that he wouldn't get to say goodbye to Mabel, and closed his eyes, preparing for the end.

* * *

><p>If it were anyone else, Bill would later tell himself, he would have let the gargoyle have them and laughed as their fragile human body was torn to pieces.<p>

He just needed the kid alive to get the journal, that was all (except he didn't). He didn't have the patience to wait for the Pine Tree to be reincarnated again (except he did; he'd done it before, too many times to count).

It wasn't like he _actually_ liked the kid. He was too nosey for his own good, after all, and had spoiled Bill's plans far too often. He was blind too, so very blind to what was right under his nose, so easily swayed by a little human weakness (because that's what it was; human, disgustingly so. How he hated it).

But the kid had spirit like he hadn't seen in years, and a burning curiosity that caused trouble more often than not, and that, at the very least, made him _interesting_. And after millenia of existing, watching (and sometimes aiding) the rise and fall of civilizations, and meeting human after witless human, finding someone that interested him was about as good as it was going to get.

Yes, if it were anyone else, Bill wouldn't have blinked an eye.

But Dipper Pines could not be allowed to die just yet.

He barely thought, barely considered what he was about to do, charging forwards at what seemed an agonizingly slow pace, yelling uselessly to _move, kid, MOVE_, and slamming into him with a tackle that would have made a varsity football player proud. Breathing a stealthy sigh of relief as he saw the kid rub his head, dazed but otherwise unharmed, he looked up – to realize that the gargoyle, momentarily confused by the disappearance of Intruder Number One, had quickly recovered, and was now charging directly at the hapless former demon who had dared to steal its kill.

Or, at the very least, it would have done so, had not a shimmering corona of blue fire exploded from his prone form, causing it to fall back, howling in pain as the flames licked across its stony hide.

Slowly, Bill's face broke into a grin so wide it seemed to defy the laws of physics. He stood leisurely, casually dusting off his suit as if to dare the wounded gargoyle to attack him. With a snap of his fingers, his cane flew upwards into his waiting hand, now glowing a bright neon yellow. A gleeful cackle escaped his lips as an imperceptible breeze began blowing around the room.

"Ohhhh, _yes_," he purred, voice carrying an echo of distant, incomprehensible planes. "This is _so much better_."

There was a brief, blinding flash, and the barest hint of a scream.

When it cleared, the only trace of the gargoyle was a large burn mark on the battered floor, and the faint scent of ash.

"You killed it," Dipper said hollowly.

Bill snapped around to face him, laughing madly and notably now sporting the catlike eyes Dipper had grown used to seeing during his romp as 'Bipper', as Mabel was so fond of calling him.

"Isn't it _great_?" he said, zooming forward until he was face to face with the deertaur, who stumbled back instinctively. "Loooooook, look look look you useless _human_, I KILLED IT."

"Hahaaaa, look at that yes you did," Dipper said, laughing nervously and not once taking his gaze off of Bill, who swooped forwards suddenly, grabbing something off of Dipper's face.

"Got your nose!" he said, flipping it between his fingers dexterously. Dipper yelped, reaching up to where the organ was formerly located. The demon cackled with amusement and snapped his fingers, replacing the nose. "I did that!" He zoomed around the room, whooping with glee, leaving Dipper to watch him with mild horror and apprehension, protectively clutching the journal's spine.

Eventually, he came to a stop, gently floating a few inches above the ground and still grinning like a madman. "HAHAAAAA, OH YES," he yelled to the empty air. "IF YOU THOUGHT YOU COULD TRAP ME IN THIS ACCURSED FLESH PRISON FOR LONG, YOU WERE _WRONG_, FLUVIUS, BECAUSE BILL CIPHER IS…" He trailed off, suddenly looking much more exhausted.

"Is…" He wavered, frowning and struggling to maintain his hover, and Dipper hurriedly ran forwards, already seeing the inevitable conclusion. No sooner had he reached the demon than he slumped gently to the ground, his eyes losing their golden tint even as they rolled back, eyelids fluttering closed over them with a strange finality.

"Bill?" Dipper said, shaking the unconscious demon. He did not stir, though the slow rise and fall of his chest confirmed he was indeed alive. Dipper looked at the prone figure, rubbing his head in exasperation and confusion.

"What just _happened_?" he whispered to the empty room.


End file.
